[PATCH] [OPENMP] Added option -fopenmp=libiomp5

[Alexey Bataev]

Alp, generated IR cannot be identical, because interfaces of gomp and 
iomp5 are different. My patch with initial codegen support for OpenMP 
constructs targets iomp5 interface. Besides, it is incomplete and I 
don't want someone run into the troubles with incomplete codegen for 
OpenMP constructs. When it will be completed we'll remove 
-fopenmp=libiomp5 option or modify it somehow.

Best regards,
Alexey Bataev
=============
Software Engineer
Intel Compiler Team
Intel Corp.

27 Февраль 2014 г. 16:32:01, Alp Toker писал:
>
> On 27/02/2014 11:58, Alexey Bataev wrote:
>>
>> ================
>> Comment at: lib/Driver/Tools.cpp:5237-5240
>> @@ -5236,4 +5236,6 @@
>> -  if (Args.hasArg(options::OPT_fopenmp))
>> +  if (Args.hasArg(options::OPT_fopenmp)) {
>>       // This is more complicated in gcc...
>>       CmdArgs.push_back("-lgomp");
>> +  } else if (const Arg *A = Args.getLastArg(options::OPT_fopenmp_EQ)) {
>> +    if (StringRef(A->getValue()) == "libiomp5")
>> ----------------
>> Dmitri Gribenko wrote:
>>> What happens if the user passes -fopenmp -fopenmp=libiomp5?
>> Then only -fopenmp will work and the warning for -fopenmp=libiomp5
>> will be emitted. I thought that we have to be conservative with
>> -fopenmp option.
>>
>> ================
>> Comment at: test/OpenMP/parallel_ast_print.cpp:3
>> @@ -2,3 +2,3 @@
>>   // RUN: %clang_cc1 -fopenmp -x c++ -std=c++11 -emit-pch -o %t %s
>> -// RUN: %clang_cc1 -fopenmp -std=c++11 -include-pch %t -fsyntax-only
>> -verify %s -ast-print | FileCheck %s
>> +// RUN: %clang_cc1 -fopenmp=libiomp5 -std=c++11 -include-pch %t
>> -fsyntax-only -verify %s -ast-print | FileCheck %s
>>   // expected-no-diagnostics
>> ----------------
>> Dmitri Gribenko wrote:
>>> If this flag only changes the linker option, then there is no need
>>> to update AST tests with it.
>> No, it also turns on OpenMP support in front end. You can consider
>> -fopenmp=libiomp5 option as an extension for -fopenmp option. My idea
>> was not only link libiomp5, but also generate the IR for libiomp5
>> runtime only if -fopenmp=libiomp5 is specified. If -fopenmp is
>> specified, the IR won't be generated (for compatibility).
>
> I'd expect the IR generated for the two runtimes to be identical given
> that the target is a stable ABI.
>
> How about just passing -lomp from the driver to the linker and leaving
> it up to distributors to symlink the implementation (GNU or Intel) to
> the generic name, the same way -pthread works?
>
> (The -stdlib= optional argument was necessary only due to the need to
> modify header search paths and select the correct ABI between the two
> C++ standard libraries simultaneously. Neither of these needs ought to
> exist with OpenMP runtimes.)
>
> Alp.
>
>>
>>
>> http://llvm-reviews.chandlerc.com/D2841
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>